In general, high-definition metal patterns have been formed by photolithography, which is a technique that enables high-definition patterning to be achieved. However, photolithography involves many problems in that, for example, photolithography requires large-scale facilities and vast capital investment since photolithography includes the steps of deposition of a metal, application of a resist, exposure through a mask, removal of the unwanted resist, etching of the metal, and removal of the remaining resist. In addition, the complex production steps limit productivity, and the procedure in which a metal film is formed over the entire surface and subsequently the unwanted portion of the metal film is removed increases the material cost and increases the environmental load.
Accordingly, there has recently been an attempt to form a high-definition metal pattern by a printing method in order to address the problems of the facility cost, material cost, and productivity in photolithography. However, metal patterns formed by a printing method have not yet been in actual use because, for example, they have lower definition than metal patterns formed by photolithography.
In order to address the problems of facility cost, material cost, and productivity in photolithography, attention has been focused on a technique in which a printing process and a plating process are used in combination (e.g., a metal-pattern-forming technique in which the surface of a support is coated with a conductive ink including a conductive substance such as silver or with a plating-core agent, the resulting coating film is fired to form a plating-core pattern, and subsequently the surface of the plating-core pattern is subjected to a plating process to deposit a metal film on the surface of the plating-core pattern) (e.g., see PTLs 1, 2, and 3).
The cross-sectional shape of the plating-core pattern affects the cross-sectional shape of the metal pattern. For example, if a metal is deposited on a plating-core pattern having an irregular cross-sectional shape, the surface of the resulting metal pattern would have a cross-sectional shape corresponding to the irregularities of the cross-sectional shape of the plating-core pattern.
For example, when the plating-core pattern is formed by screen printing, which is a technique that may cause undulations due to the matrix of mesh, undulations may occur also in the surface of the resulting metal pattern and, as a result, the metal pattern may have a D-shaped cross section or a coffee-stain-shaped cross section. When a plating-core pattern is formed by IJ printing, the resulting metal pattern also has a D-shaped or coffee-stain-shaped cross section. The unevenness of thickness in a metal pattern may cause various problems.
The metal pattern, which is a laminated body including a plating-core pattern, requires good adhesion at each interface among a printing object, the plating-core pattern, and the plating-core pattern. However, a laminated body that satisfies all the above requirements has not yet been developed.